doc: update size of "hello, world" binary in FAQ

Fixes #17159

Change-Id: I44d7081ef7a973dcd1cc2eb7124e3454c94bc6e3
Reviewed-on: https://go-review.googlesource.com/31770Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

doc/go_faq.html

@@ -1770,7 +1770,7 @@ A simple C "hello, world" program compiled and linked statically using gcc
 on Linux is around 750 kB,
 including an implementation of <code>printf</code>.
 An equivalent Go program using <code>fmt.Printf</code>
-is around 2.3 MB, but
+is around 1.5 MB, but
 that includes more powerful run-time support and type information.
 </p>